IBM 5170 Motherboard - ROM information
Type 1 motherboard
On early 5170 motherboards of type 1, there are four 16 KB sized BIOS ROM chips (of type 27128), in sockets U17/U27/U37/U47. (photo)
Accordlingly, shunt block U131 is set to the '27128' position.
Later, two 32 KB sized BIOS ROM chips (of type 27256) were supplied instead, one in socket U27 and the other in socket U47.
Accordlingly, shunt block U131 is set to the '27256' position.
Type 1 motherboards were supplied with the 01/10/84 revision of BIOS. Additional information about that is at here.
6 MHz motherboard. Required are ROM's of a maximum access time of 260 ns. (source)
Type 2 motherboard
On a type 2 motherboard, there are two 32 KB sized BIOS ROM chips (of type 27256), one in socket U27 and the other in socket U47.
These motherboards were supplied with the 06/10/85 revision of BIOS. Additional information about that is at here.
6 MHz motherboard. Required are ROM's of a maximum access time of 260 ns. (source)
Type 3 motherboard
On a type 3 motherboard, there are two 32 KB sized BIOS ROM chips (of type 27256), one in socket U27 and the other in socket U47.
These motherboards were supplied with the 11/15/85 revision of BIOS. Additional information about that is at here.
8 MHz motherboard. Required are ROM's of a maximum access time of 190 ns. (source)